"So, how would we like to do this?" Luna asked impatiently, her recently-denied orgasm making her more than want to earn it, but seeing her sister only shrug. Luna had just been given a great blowjob by her sister Celestia, Celestia's estrus egging them both on to show another side to each other, a side that was clearly barely contained for many, many years. A lust for each other that was now culminating to the most intimate act possible.

"I'll take you however you please, so long as that big dick ends up inside me," Celestia replied, and, her urges once more taking hold, started kissing her sister Luna softly again, a chain of brief, yet deep kisses while her hips started to grind against Luna's again.

To Celestia's slight disappointment, Luna made motions to get up, to which she allowed. She watched as Luna got off the bed, and seeing her stallionhood hanging stiff and ready made her lick her lips at the sight. "Well, we could do it dragon-style*. That is a very intimate position, chest-to chest like we were. Or, perhaps you wish me to mount you, to take you as our ancestors mated?" Luna asked, watching as Celestia seemed to make a decision.

In response, Celestia assumed the position she desired, raising her hips to accommodate Luna's slightly smaller body as she laid on her back in the position her sister suggested. "Like this. I want you to mount me like this," Celestia said simply, and seconds later she felt Luna on top of her, her rod rubbing up against Celestia's very wet snatch.

As Luna felt Celestia's heat-swollen lips pressed to her glans again, her member throbbing in reaction as it winked on her flare in a kiss, something occurred to her; a moment of clarity through the fog of pheromones, realizing that she wasn't wearing a condom, Celestia wasn't using protection, and with just how fertile Celestia smelled... "S-sister, you're in heat...shouldn't we use some sort of foal-prevention?" Luna asked, though in reality she wanted nothing more than to see Celestia's barrel swell with her foal, to Tartarus with what other ponies may say.

Celestia stayed silent, thinking, but knew the instant she hesitated in saying 'yes' that she wanted this. "Just...hurry up and fill me, Luna. I need you inside me, now please," Celestia whined, squirming a bit underneath her, slightly annoyed at the position they were in now because she was pinned and couldn't make her put it in; completely at her smaller sister's whims and more turned on because of it.

After she didn't hear Celestia demand contraception, Luna smiled a little at the implications; that she may want to recieve a foal from her. If not, there was always the 'after-sex' spell that could be used. Either way, Luna finally realigned herself, before shifting her hips slowly forward.

Luna moaned softly as she felt her sister's warm pussy-lips spread around her flare, warmth and slickness surrounding one of her most sensitive parts. She could swear she was dreaming this, but she knew a dream could never feel this good. Her own clit slowly winked as well, a stream of her own feminine fluids drooling down her leg as Luna penetrated her sister.

Celestia slowly laid her head back into the mattress and purred quietly upon feeling Luna's flare pop into her, the rest of her shaft parting her lower lips quite easily and sliding in smoothly given just how much lubrication she'd made. How thick her mucous was, and how easily she accepted then clamped down on her member, told her 'stallion' just how fertile she was; likely ovulating right then, her fluids thick to welcome Luna's sperm right up into her fecund uterus to meet with her egg. To fertilize it. To make her a mother again, as she hadn't been for too many years. "Yes, sister. Fuck me. Please. You have no idea how much I need you right now." Celestia whispered passionately, kissing the side of her sister's muzzle as both panted from the sensations down beneath them.

Luna's girth was perfect and not too thick, filling Celestia up just right as it ever so slowly slid further, filling the void within her with just what it needed. It felt as if Luna's stallionhood was custom-made for her marehood, so filling but that stretching not painful at all.

Celestia's front hooves snaked around Luna's neck as its medial ring kissed softly to her entrance, then passing it and filling her up just that little more. She planted her lips on Luna's again, as the sensation of it rubbing over her clit rolled through her, wanting to kiss her while they made love for their first time. Everything felt perfect for her.

The secret fantasies of them doing something like this ever since she'd hit puberty and realized the significance of Luna's secret trait were now fulfilled, something Celestia thought impossible given their familial relationship. "Luuuuna..." Celestia moaned; moaning her sister's, her lover's, name in between kisses.

Luna sighed as she slid herself more into her sister's welcoming, hot, tight passage, feeling it kneading and hugging all over her. "You're so hot inside...feels so good and tight..." Luna whispered sensually, before getting impatient and pressing herself the rest of the way into her, hilting her.

Celestia meanwhile felt as Luna pressed her flare gently against her cervix, feeling like it was pressing against her belly button she went so deep. They fit together perfectly, as though their parts were made for each other, "...it feels...amazing."

It had been so long since the last time Celestia had a stallion help her with her heat, and it certainly was not as fulfilling as what Luna was giving her now. Most ponies didn't interest her romantically, and while she knew romance wasn't the main point of sex during estrus, she'd always preferred to do it with somepony she truly loved.

Celestia wanted her sister more than just as a semen donor to relieve her estrus and fool her body into thinking she'd made a foal. She loved her dearly, and would even actually bear her foals if Luna wished it, no matter what other ponies thought.

For Luna, having sex with Celestia felt much different than anyone else she'd been inside, or had inside herself, before. So much more meaningful and special, her love for her so intense she truly wanted to get her pregnant. Speaking of... "M-May I start?" Luna asked, feeling as her sister’s nearly-hot insides rippled around her stiffness.

"Do as you please...just don't hold back. I need you so badly," Celestia whispered back, "I love you."

Luna felt as she was balls-deep inside her sister's hot, hot passage, feeling her body squeezing on her member near-constantly as she held still, letting her acclimate to her tightness. After a moment's pause, Luna started rocking her hips slowly, millenniums-past experience twinning with instinct as she slowly humped into her sister. She pulled out partially so her medial ring exited, before swiftly hilting herself again, being rewarded with a wink and a tight squeeze from inside Celestia. "Faster, more, please," Celestia whimpered, grunting in satisfaction as Luna gave a harder thrust in response.

Luna wasn't thinking about other ponies at the moment, nor the foal that could result from this; she was simply thinking of the heated mare between her forehooves and the sweaty chest beneath her own, Celestia's foal-passage so delightfully, eagerly kneading her stallionhood of its seed as soon as it'd penetrated her.

Luna kept up her slow but firm thrusts, fulfilling her sister's instinctive and emotional needs as well as her own. "I love you Cellie, more than a sister..." she whispered lovingly, bringing her in for another soft kiss as they bred, her pace picking up a little more at her insistence.

"You're doing wonderfully, Luna, and I love you too," Celestia sighed pleasantly, enjoying the slow, firm pace Luna was taking, but knew that it wasn't enough; not enough for her, or her heat, to be fully satisfied. Lighting her horn again, she gave her sister's butt a playful squeeze and pushed it down a little, making Luna hilt her a little rougher than she had originally intended to. She gave a moan in sync with her sister’s, feeling glad that the increased pleasure was mutual. "A-aaah... a little bit rougher please?" Celestia half-pleaded, her back hooves kicking a little from that one sudden burst of stimulation.

Noticing the magic on her rump pressing her hips forward just that once drove Luna on, making her thrust harder, and she nodded softly to Celestia's request. Setting her hips to a mid-paced rhythm, Luna moaned softly at the more powerful sensations as her rod dragged through her sibling's tight, ribbed canal, feeling it constricting it in the best way. The scent of a fertile mare drove her on, her cock throbbing, squirting another shot of pre-cum into the small puddle of it forming inside her sister. That alone was likely enough to impregnate her already but Luna was nowhere near done yet, her body wanting to seal the deal.

It was a wondrous feeling as Celestia felt filled up by somepony she loved, her heart swelled with a warmth that she had rarely felt in her lifetime. Butterflies danced around in her stomach as she felt the tingling pleasure within her pussy, feeling Luna sliding in and out almost effortlessly yet setting her alight with pleasure. She knew now that she truly loved Luna as a lover, not just a sister. Knowing it wasn't just her heat goading her actions. "You feel wonderful, Lun-aaaah...!" Celestia yelped as a wink timed perfectly with Luna's ring passing over her love button, the intense stimulation making her squirm underneath her sister. "That's...m-much b-better...mmmpf...k-keep doing that."

Kissing Celestia's neck and lips, wherever her lips would land really, Luna kept that moderate pace for a long while. As she felt the end drawing closer and closer, she held longer, more loving kisses, shifting so she could up her thrusts to be balls-deep and rapid, Celestia's legs meanwhile crossing over her croup and holding her in. She also felt as Celestia’s magic crept between her legs, rubbing then filling her pussy with tingling magic too, doubling down on her pleasure. Her own marehood squeezed down on it, doubling the sensations as she was fucking and was fucked at the same time.

In a few more minutes of rapid fucking, Luna grew close again, teetering on the brink, starting to flare more inside as Celestia's inner walls grew tighter still around her. Celestia's squeezes and winks were growing more rapid as well, her moans getting more and more desperate and forced as well, her panting getting more ragged.

"I'm...I'm getting close again Cellie, but I'll try to hold off so we can finish together..." Luna muttered, keeping her rapid pace for a while before slowing significantly as she nearly climaxed, resting as she throbbed hard, flared inside of her sister's passage. As she'd rested, her magic gently rubbed on Celestia's teats, clit, and wings.

Celestia loved all of the extra attention Luna gave her, feeling pampered in a way she'd never gotten before with her previous stallions. Most would just lick her enough to get her wet enough to penetrate, or not at all if she was soaked like she usually was in heat, then hump for a couple minutes, and finally blow their load inside her, not caring much about her pleasure so much as their own. Their semen calmed her estrus, silenced the urges for her to find a stallion to give her a foal for a while, so she didn't complain. Plus, she generally got to orgasm on round two. Luna, however, was doing everything in her power to let Celestia climax with her; the labor of a true lover.

"M-mmmmm, I'm getting c-closer, love. I can feel you're f-flared nice and big for m-me..." Celestia groaned in a higher-pitched whimper, her contractions getting closer and stronger, her passage growing tighter as she winked frequently, her breathing increasing; all the signs of a mare nearing her climax. The feeling of her flare swollen again, preparing to dam her up with her seed, was incredibly arousing. Her pleasure grew more and more with each stroke. Her entire body trembled lightly with the intensity of feeling her ‘stallion’ flaring. She knew Luna wouldn't last much longer. "You can cum in me..." Celestia moaned out, the thought of not getting filled up unthinkable in her breeding haze.

"A-are you sure, sister? You're in heat, s-so that m-means..." Luna said, all the while humping fast enough to make her balls slap wetly against Celestia's soaked rump. She knew no other mare that she'd want to be with like this except Celestia, no other mare she wanted to have her foal more than the mare she loved most. She loved her deeply and wouldn't hesitate to give her a child, but was worried if this truly was what she wanted and not just the heat forcing her hoof. Even then, her hips did not slow, almost like she couldn't make them, with just how close she was to release making it just so tempting to just take one more hump, than another.

"A-Aaah...yes, c-cum in me...but if you cum before me, you better be able to go again soon," Celestia cooed, her grinds getting more intense, making sure Luna was hilting all the way each time and not leaving a single inch outside her. She bit her lip at the thorough filling Luna's dick gave her, her back legs helping Luna reach a rutting pace now as she neared her own limit, the ridge of her swollen flare digging into some rather nice spots inside of her now with each pass of it over her G-spot.

She could feel Luna pulsing rather hard inside her, with her thrusts getting more desperate, knowing she must have been closer than she herself was. "Don't worry...just go ahead and finish Lu-Lu...we have all night for me to cum too," Celestia comforted, starting to thrust her magic faster inside Luna, pleasuring both her mare and stallion parts simultaneously.

Her hips kept rocking, her flare at its fullest as Luna felt her sister's vaginal clenches growing closer, fighting with all of her might to wait for her to cum, using her magic to keep stimulating her elder sister. "I...can...can go again after a b-break...I just...I can't..." Luna promised, knowing a mare's pheromones were a very powerful aphrodisiac; knowing she would be rock hard and ready again after the first orgasm with a few minutes' rest. She always was.

"Hnmm-good. Now, just finish strong for me. C-cum in me, make me cum too..." Celestia said in a shaky voice, tingles going up and down her spine. Her pussy was twinging around Luna's flared stallionhood, her legs starting to tense up as she moaned much more openly and consistently when Luna's softened flare expanded her inner walls significantly once more. Her hips bucked up into her sister’s thrusts more, her legs kicking out randomly at the instinctively-telling sensation of her stallion flaring inside of her again; that spreading telling her that Luna was getting ready to make her a mother. Celestia loved that feeling almost as much as an orgasm.

Luna felt light touches on her testes as Celestia clearly goaded her on with feathery flicks of her magic, the extra stimulation making her cock flex and stimulating both of them more as they got closer and closer to their climaxes. Celestia's clit winked more feverously in her sister's magic, her body quivering with excitement.

"I'm very c-close! C-cum Luna, Please...c-cum for me, my beautiful stud!"

"I-I can't take much m-more!"

Celestia's back hooves instinctively locked around Luna's croup, holding her closer and keeping her cock inside so each thrust was only an inch back and forth, her passage doing the same to Luna’s member. Each thrust from Luna was like a mini-orgasm now, Celestia's body spasming for a moment as she even squirted a little, making herself that much more slick. All she needed to enter her ecstasy were a few more thrusts.

"D-don't stop for Faust's sake don't stop!" Celestia barely forced out in one breath, her wings spreading and erratically flapping, her fluids practically spilling out like somepony tipped over a water bucket as she intentionally squeezed down on Luna, trying to set her over, "I'm... I'm cumming, Luna! Make me a mother!"

As she heard such lewd words coming from her sister, Luna let out a deep breeding whinny as she hilted herself a final time, her slightly-protruding urethral opening once more kissing the entrance of Celestia's cervix as her passage milked her tightly for her seed. She would give it only too gladly. Luna held her sister's barrel tight as she remained hilted, her cock stiffening, then throbbing harder, harder...

When she felt those-oh-so-wonderful involuntary contractions in her pelvis, Luna went silent, feeling the pumping of her cock, the throbbing of her balls, as she unloaded shot after shot of her virile Alicorn sperm into her sister's waiting womb. She bit her lover's ear on reflex to cope with the sheer pleasure she felt, her sister's cervix meanwhile dipping down, kissing her flare to bring her cum up into her womb.

It had never felt that good before to cum for Luna, her heart pounding as she held onto her sister for dear life. Meanwhile, her passage went into its own contractions around her sister’s still-pumping magic, giving Luna both a male and female orgasm at the same time.

Luna's shaft never seemed to stop pumping into her sister's ripe womb, painting her fecund uterus's and pussy's walls white in her sticky, life-giving cum. Her back legs started to wobble slightly as she felt each gush after gush of thick, potant seed being taken from her and entering deep inside of her procreant mare's furthest depths. This was different than any other mares she'd slept with before. She loved her sister. Luna did something this time that she'd never done for another pony during sex before; she put her muzzle within an inch of her sister's ear and whispered something to her. Four little words.

"I love you, Celestia."

"I L-LOVE YOU LUNA!" Celestia cried out as her sister's flare pressed firmly to what felt like her belly button, Celestia knowing instead it'd likely hit her cervix. Her head tilted back into the mattress as the rhythmic pump-pump-pump of her sister cumming in her reverberated through her squeezing inner walls, feeling thick warmth pooling farther within her, and Celestia felt a sense of primal gratitude for such a gift.

Hearing the declaration of love from her sibling, and the feeling of her unprotected insides being coated with sprays of warm, gooey relief, finally set Celestia over. She gave an especially hard tremor as her depths were filled, letting out a deep groan as spurt after spurt entered into her womb, able to feel it all landing within her depths; so much cum it could have been two stallions unloading inside her at the same time.

Celestia's lower belly was feeling quite pleasantly filled and warm now, that warm feeling increasing with each new spurt of the incestuous cum into her belly, her passage now involuntarily, ceaselessly clenching onto the rhythmically throbbing length of Luna’s stallionhood and claiming all she had to give. Luna's large and growing donation had left her heat cooled and Celestia felt nothing but warm, tingly, and wonderful inside as her insides milked everything they could from the spurting 'stallion' within her, her constant, grasping contractions making her writhe in pure bliss as her body claimed its stallion's foal.

At that moment, Celestia knew the best feeling she'd felt in her entire life. She knew the feeling of being one with the pony she truly loved most.

Luna kept humping shallowly, reticent to move even an inch from that milking warmth she was embedded into. She could feel Celestia's body milking her of her seed, accepting her to-be foal into her womb. Eventually, unfortunately, her gushes ended, simply leaving her fully flared and pressed up against her mare's cervix, her swollen flare keeping the full load of her thick foal-cream plugged up within Celestia's womb as nature had intended it to. As she was coming down from her twin orgasm, feeling physically emptied yet so emotionally full at the same time, Luna meanwhile kissed all over Celestia's muzzle, before once more ending it on her lips.

Their post-coital kiss was soft and chaste to contrast the absolute rutting they'd been doing, Luna's eyes closed as she still felt Celestia's inner muscles tugging on her, trying to wring more seed to make a foal with deeper into her lightly-swollen womb, though she had no more to give right then. "I love you..." Luna repeated after their kiss ended, pausing to give her sister another kiss on the nose, "...love you, love you, love you."

"Do you really?" Celestia asked, her serious tone taking Luna aback. Now that her mind was clear of her lustful needs, her estrus sated, she was able to think about this all while they rested. "Perhaps, all of this was a result of my pheromones calling you to simply breed the fertile mare, like all of those other mares you admitted to me that you've bred since your return. Those mares you gave a foal to before in disguise at those ‘Canterlot breeding parties’. All those princes and princesses out there, not even knowing they're royalty," Celestia paused, meeting her sister's eyes with a steely gaze, " Tell me sister; this 'love', is it just the influence of my pheromones on your mind, driving you to say things like this? You've never showed any signs of loving me like this before my heat. You were everything a sister should be, and nothing more."

Luna was quite taken aback by the accusation, that these feelings she admitted being called into question about their authenticity, dismissed as simply being pheromone-driven. Her stallionhood's hardness wilted now, Luna's penis slipped free from her sister's slightly-gaping pussy with a quiet, wet pop, Celestia leaking a small amount of stallion-cream from within her.

Instead of responding instantly, Luna instead shifted them on the bed, moving so they were in an awkward spooning position, taking big spoon despite Celestia's larger size making it harder to wrap her hooves around her. "Luna, tell me now, please. Is this...is this all just a 'seasonal' thing, merely because I was in heat and you couldn't hold back anymore?" Celestia asked, getting a quiet sigh from Luna.

"Well, yes and no, Cellie. Yes, I couldn't hold back my lust for you, and no, this isn't merely a 'seasonal thing'," Luna replied, feeling Celestia squirming a little, feeling the wetness of her semen leaking from her and onto Luna's stifle, "I've always loved you more than as merely a sister, but I just never showed it because...well, first because our parents said it was wrong, and then, for a while...I truly did hate you," Luna saw Celestia's ears fold back at that, "When ponies loved your day and disregarded my night....that hurt me, being ignored like that while you were loved by everypony. Being ignored by you though, sister, hurt the most though."

"Sister, I still loved you then. You were just so blinded by your jealousy of me you couldn't see that. I tried to tell you, but you were already influenced by the Nightmare at that point, and then..." Celestia paused to sob, feeling hot tears coming to her eyes, "...I...I had to send you away. You have no idea how much I missed you, little sister, during those thousand long years without you. How lonely you must have been, too...it pains me to imagine that."

Luna sighed softly, feeling her own eyes welling up, before softly shaking her head, "That is in the past now, sister. Bygones. I am here now, you are here, and I still love you very much, sister," Luna paused thoughtfully, before making a decision. "Celestia, I would gladly accept you as my mate. My wife. If you so choose, I would also like for you to be the carrier of my foal. Mother to our foal who could possibly be another immortal alicorn, if it works like it did with Princess Cadenza and her daughter Flurry Heart."

Celestia was taken aback by the sudden proposal and suggestion of actually carrying her sister's child, but deep inside, she knew that was what she wanted. That she wanted to be Luna's and Luna to be hers, forever, and for her to carry her foal. "But..." Celestia started, before feeling Luna squeeze her a little tighter, silencing her.

"I will be beside you no matter what happens after your estrus ends, and no matter what you choose to do with my seed. I will always be beside you, as mother of my foals, as my wife, or simply as my loving sister. Always." Luna said, and Celestia could feel a new wetness on her back, hearing Luna sniffling too.

As she heard that, Celestia rolled over to face Luna, seeing her eyes glistening with tears and her cheeks' fur wet with the same. She pulled her little sister into a hug then, nuzzling into her neck softly and giving a content nicker. "I will gladly carry your foal and be your wife, Luna, because I really do love you too, the same way you love me." Celestia felt like this all was a dream. She'd been so afraid Luna would hate her forever back when she'd had to imprison her on the Moon. But here they were now, having had sex, declared their love, and Celestia would likely soon to be carrying the foal of her sister, her fiancée.

"B-but what about the other ponies? What would they think of their two princesses getting married? Then they'll learn that the foal is mine, and...they’ll know I’m more than just a mare..." Luna started, only to be startled into muffled mumbles followed by silence as Celestia once more met lips with her, kissing her as only a lover could.

"Forget about the other ponies for now and just think of us. We're together now, and nopony or nocreature will get in the way of that." Celestia said with a conviction in her words, pulling Luna closer as she rubbed her nose against her sister's, just like she used to when they were foals.

Luna meanwhile felt her heart flutter as she was held like that, feeling a certain pride in hearing that Celestia would carry her foal. She couldn't agree more that nopony else's opinion of them mattered as she lay there together, holding each other close, sharing their afterglows. Feeling Celestia's chest expanding against her own as her breathing calmed, her heart thudding against her chest...nothing would ever compare. "I love you so, so much, sister..." Luna whispered as tears stung her eyes again, burying her muzzle into Celestia's celestial mane after giving her new fiancée another soft, grateful kiss. Grateful for her accepting her, not only as her mate and foal-to-be's sire, but also as her sister. Her lover. Speaking of loving...

"Sister, I'm hard again." Luna said and, sure enough, her erect stallionhood was sandwiched between their chests, ready for round two. Neither had really noticed as they'd confessed their love to each other how much that was affecting their bodies, Luna fully erect again and Celestia feeling her heated need coming back again.

Celestia looked up with an amused expression, stopping her nuzzles to look between them at Luna's once again hard member. Celestia's heat reacted accordingly to the sight and scent of her mate's arousal, reawakening the fire that had just been doused inside of her so recently. "Already? I thought you said you'd need a break? But since you don't..." Celestia said, casting a quick spell. An aura surrounded her, shrinking her to roughly her sister's size.

Seeing Luna look at her with a puzzled expression, Celestia stood and placed her back legs at either side of Luna's head, her flank hovering above her muzzle with her own muzzle at her cock. "I never got to taste you last time, and now seems like the best time to get a taste of each other," Celestia asked, looking to Luna, "don't you think?"

"Sister, I would love that," Luna said, seeing Celestia smile in kind. Luna's cock throbbed, then she moaned as Celestia took her flare into her mouth once more.

Celestia moaned too as she felt Luna’s muzzle bury into her creamed pussy, suckling her sister’s cock, tasting her own fluids and Luna's sperm on it.

It was going to be a long night, and neither could wait. For more passionate sex, and for what the future may hold for them. Together.

Author's Note

* - missionary.

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If you enjoyed this story, please drop a like.

I may or may not continue this, as there's more of the RP this was based on left, but I'm quite busy and barely got even this done. We'll see, but for now I'm leaving it as a one-shot, as it will likely remain for a very long time. Hope you all liked it!

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Until next time, I'll see you all in the comments section or my next story. Au revoir et à bonne nuit chaque-poney!!!